Tyrone Wells, under the supervision of Professor Art Ragauskas, is working on the development of lignin as a precursor towards the generation of high-molecular-weight materials (HMW) and biofuels. Kraft lignin can be repurposed for the generation of HMW materials such as carbon fibers and adhesives. However, in order to optimize the mechanical properties of these lignin-derived materials, the conversion processes benefit from an upgrading procedure that increases the degree of polymerization of the starting material. An exciting aspect of the work focuses on the use of ultrasonics as a novel and efficient means to rapidly increase the degree of polymerization of lignin for HMW applications.

Meanwhile, the degradative conversion of Kraft and EOL lignin toward low-molecular weight compounds has yielded components that are apt for specific microbial uptake by soil bacteria and sub-sequent metabolism. Remarkably, some heterotrophic soil bacteria employ a metabolic sequence known as the beta-ketoadipate pathway that can aerobically convert aromatic compounds into lipids that are suited for biodiesel applications. Moreover, certain species within this group are oleaginous, and are capable of producing over 20% of their cell dry weight in single cell bio-oils. Accordingly, another facet of the work focuses on adapting oleaginous organisms to low-molecular-weight lignin as a development strategy for large-scale biodiesel production.

Development of precursors initially requires the isolation of lignin from lignocellulosic biomass, which is performed via ethanol organosolv pretreatment, or the extraction of lignin from black liquor derived from the Kraft pulping process. Both ethanol organosolv lignin (EOL) and Kraft lignin are then thoroughly characterized by means of gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The ultrasonic-polymerized lignin is characterized via GPC, FTIR, and NMR.